These studies are directed at the exposure of subjects at increased risk for sudden cardiac death (SCD) and at the protection of patients with malignant ventricular arrhythmia (non-infarct related ventricular fibrillation or hemodynamically compromising ventricular tachycardia. The major goals for the coming year are: (1) Determination whether suppression of advanced grades of VPBs protects against sudden death; (2) Assessment of the significance of elimination of the myocardial repetitive ventricular response (RVR) as an indicator of control of electrical instability; (3) Continued optimization of antiarrhythmic drug usage for control of malignant ventricular arrhythmias; (4) Further aggravation; and (5) Examination of methods for exposing myocardial electrical instability.